Subcritical water extraction followed by liquid chromatography mass spectrometry for determining terbuthylazine and its metabolites in aged and incubated soils

Due to the great potential of atrazine in contaminating groundwater, its us e has been banned in several countries and often replaced by terbuthylazine (CBET). Little is known on the fate of CBET in soil. The purpose of this w ork has been (1) to develop a general method for analysing CBET and its deg radation products (DPs) in soil and (2) to use this method for elucidating the fate of CBET incubated in both surface and subsurface samples of an agr icultural soil which had been receiving repeated CBET spills. This method i nvolves analyte extraction from soil at 100 degrees C by phosphate-buffered water. Analytes coming out of the extraction cell were collected by a grap hitized carbon black extraction cartridge. After analyte elution with a sui table solvent mixture, the final extract was analyzed by LC-MS. From an age d soil, our method extracted altogether quantities of CBET and its DPs resp ectively 2.1 and 1.4 times larger than those by two previously reported met hods. For the analytes considered, limits of quantification (S/N 10) ranged between 0.22 and 5.5 ng per gram of soil. The laboratory CBET degradation experiment showed that (1) similarly to atrazine, remarkable amounts of hyd roxylated metabolites were formed; (2) when the subsoil microflora was in t he presence of rather large amounts of CBET, it degraded the herbicide with a rate similar to that of the topsoil microflora.